This invention relates, generally, to spindles and, more particularly, to a spindle which may be used with a diskette storage device drive.
Spindles for disk storage apparatus having pre-loaded ball bearings have been used for a significant period of time. Generally, they consist of a shaft having a force-fitted receiving part thereon with the receiving part being used to receive magnetic diskettes or the like. A rotatable shaft is mounted in a housing through the use of customary ball bearings which are axially pre-loaded towards each other by springs. The drive motor is generally attached on the end of the shaft opposite the receiving part. However, this has been found to have certain basic disadvantages.
In some present day embodiments, for space considerations in the axial direction, the mounting arrangement together with a housing has been utilized in conjunction with lengthened receiving parts. However, since magnetic disks have a standardized or given inside diameter, the radial space remaining for all machine parts arranged within the receiving part is very small. This resulted in a shaft of reduced diameter with the result that dynamic flexibility occurred. This was generally not as problematic in early drive devices since the radial spacing of information on the diskette and hence the volume of information stored thereon was relatively small. However, present day disk devices are on the order of at least four to eight times more powerful than earlier devices with the result that spacing of information is much more dense. Accordingly, dynamic flexibility caused by a reduced diameter shaft may result in errors when information is read from the magnetic medium. Further, present day arrangements use a large number of individual parts such that inaccuracies can and do result due to the accumulation of tolerances. This thereagain produce impermissibly noisy operation as well as travel of the spindle which is not as precise as necessary. The springs which act in the axial direction also produce dynamically unstable systems in some circumstances and at different periods of time. Additionally, large numbers of individual parts also result in expensive assembly costs of the spindle unit.